Multitemporal optical and radar metrics for wetland mapping at national level in Albania.

Wetlands are highly dynamic, with many natural and anthropogenic drivers causing seasonal, periodic or permanent changes in their structure and composition. Thus, it is necessary to use time series of images for accurate classifications and monitoring. We used all available Sentinel-1 and Sentinel-2 images to produce a national wetlands map for Albania. We derived different indices and temporal metrics and investigated their impacts and synergies in terms of mapping accuracy. Best results were achieved when combining Sentinel-1 with Sentinel-2 and its derived indices. We reduced systematic errors and increased the thematic resolution using morphometric characteristics and knowledge-based rules, achieving an overall accuracy of 82%. Results were also validated against field inventories. This methodology can be reproducible to other countries and can be made operational for an integrated planning that considers the food, water, and energy nexus.

Modelling the impact of land use management on water resources in a tropical inland valley catchment of central Uganda, East Africa.

A combination of climate change, food demand, population growth, and other driving forces are causing land use and land cover change (LULC) in wetlands of Sub Saharan Africa (SSA). This has a profound effect on water resources, thus it is imperative that such consequences arising from these changes are predicted accurately to support land use management. For that, local scale studies are required to understand the system and to perform scenario analysis. The focus of this study was on small scale inland valleys which are common in SSA. The impact of LULC on the hydrological processes in a tropical inland valley was investigated. A hydrological response unit (HRU)-based (ArcSWAT2012) and a grid-based setup (SWATgrid) of the Soil Water Assessment Tool (SWAT) model are applied. Good model performance was achieved after calibration and validation with daily discharge (R2 and NSE > 0.7 for both model setups). Annual water balance indicates that 849.5 mm representing 65% of precipitation is lost via evapotranspiration. Surface runoff (77.9 mm) and lateral flow (86.5 mm) are the highest contributors to stream flow in the inland valley. Four land use management options are developed in addition to the current land use system, with different water resources conservation levels (Conservation, Slope conservation, Protection of headwater catchment, and Exploitation). There is a strong relationship between the first three management options with decreasing surface runoff, annual discharge and water yield while the fourth option will increase annual discharge and total water yield. This suggests that if poor management and increasing exploitation of the inland valleys persist, the availability of water resources for human consumption and plant growth will decrease. This study contributes to improving the scientific knowledge on the impact of land use change on hydrological processes in the catchment-wetland nexus to support sustainable water resources management.

Health risk perceptions and local knowledge of water-related infectious disease exposure among Kenyan wetland communities.

BACKGROUND: Risk perceptions have the potential of motivating and shaping health-related behaviour, i.e. the application of protective health measures. They may reduce or accelerate the risk and exposure to diseases and are therefore valuable, particularly in environments such as wetlands that entail multiple risk factors exposing humans to disease-causing infectious agents. METHODS: We assessed the risk perceptions towards infectious disease exposure in the Kenyan Ewaso Narok Swamp and evaluated whether the perceived risks reflect the actual risk factors. Data were collected from community members (target population, experts) by different methods (cross-sectional survey, in-depth interviews). RESULTS: The overall level of risk perception regarding the contraction of diseases in the wetland was high. Exposure to water-related infectious diseases was understood as being driven by users' physical contact to water during wetland use, characteristics of pathogens and vectors of disease, both in domestic and occupational environments. The risk factors mostly associated with diseases in wetlands included the limited access to basic water supply, sanitation and poor (environmental) hygiene (WaSH) (typhoid fever, diarrhoeal diseases, schistosomiasis), agricultural irrigation (malaria), the pastoralists' proximity to livestock (trachoma), the use of agrochemicals (skin and eye diseases), seasonal flooding (malaria, typhoid fever) and droughts (trachoma). Different user groups, i.e. farmers and nomadic pastoralists, perceived the use-related risks differently and different (occupational) risks were attributed to different groups. The understanding of disease exposure as due to the intense hydro-social interactions and change present in the fragile semiarid wetland was clear. CONCLUSIONS: By showing that the risk perceptions reflect the actual risks and shortcomings, this study underpins the vital role of wetland users as key informants. It demonstrates that risk perception studies and resulting recommendations from the grassroots level serve as helpful supportive tools for health-promoting wetland management which requires a sensitive, integrative approach that takes into consideration any and all of the humans, ecology, and animals affected (= One Health).

Modeling the effect of land use and climate change on water resources and soil erosion in a tropical West African catch-ment (Dano, Burkina Faso) using SHETRAN.

This study investigates the effect of land use and land cover (LULC) and climate change on catchment hydrology and soil erosion in the Dano catchment in south-western Burkina Faso based on hydrological and soil erosion modeling. The past LULC change is studied using land use maps of the years 1990, 2000, 2007 and 2013. Based on these maps future LULC scenarios were developed for the years 2019, 2025 and 2030. The observed past and modeled future LULC are used to feed SHETRAN, a hydrological and soil erosion model. Observed and modeled climate data cover the period 1990-2030. The isolated influence of LULC change assuming a constant climate is simulated by applying the seven LULC maps under observed climate data of the period 1990-2015. The isolated effect of climate scenarios (RCP4.5 and 8.5 of CCLM4-8) is studied by applying the LULC map of 1990 to the period 1990-2032. Additionally, we combined past modeled climate data and past observed LULC maps. Two chronological and continuous simulations were used to estimate the impact of LULC in the past and in the future by gradually applying the LULC maps. These simulations consider the combined impact of LULC and climate change. The simulations that assumed a constant climate and a changing LULC show increasing water yield (3.6%-46.5%) and mainly increasing specific sediment yield (-3.3%-52.6%). The simulations that assume constant LULC and climate as changing factor indicate increases in water yield of 24.5% to 46.7% and in sediment yield of 31.1% to 54.7% between the periods 1990-2005 and 2006-2032. The continuous simulations signal a clear increase in water yield (20.3%-73.4%) and specific sediment yield (24.7% to 90.1%). Actual evapotranspiration is estimated to change by between -7.3% (only LUCC) to +3.3% (only climate change). When comparing observed LULC and climate change alone, climate change has a larger impact on discharge and sediment yield, but LULC amplifies climate change impacts strongly. However, future LULC (2019-2030) will have a stronger impact as currently observed.

Comparing ∆Tmax Determination Approaches for Granier-Based Sapflow Estimations.

Granier-type thermal dissipation probes are common instruments for quantifying tree water use in forest hydrological studies. Estimating sapflow using Granier-type sapflow sensors requires determining the maximum temperature gradient (∆Tmax) between the heated probe and the reference probe below. ∆Tmax represents a state of zero sap flux, which was originally assumed to occur each night leading to a ∆Tmax determination on a daily basis. However, researchers have proven that, under certain conditions, sapflow may continue throughout the night. Therefore alternative approaches to determining ∆Tmax have been developed. Multiple ∆Tmax approaches are now in use; however, sapflow estimates remain imprecise because the empirical equation that transfers the raw temperature signal (∆T) to sap flux density (Fd) is strongly sensitive to ∆Tmax. In this study, we analyze the effects of different ∆Tmax determination approaches on sub-daily, daily and (intra-)seasonal Fd estimations. On this basis, we quantify the uncertainty of sapflow calculations, which is related to the raw signal processing. We show that the ∆Tmax determination procedure has a major influence on absolute ∆Tmax values and the respective sap flux density computations. Consequently, the choice of the ∆Tmax determination approach may be a significant source of uncertainty in sapflow estimations.

Vulnerability and adaptation to climate change in the Comoe River Basin (West Africa).

Climate change is impacting water users in many sectors: water supply, farming, industry, hydropower, fishing, housing, navigation and health. Existing situations, like population growth, movement of populations from rural to urban areas, poverty and pollution can aggravate the impacts of climate change. The aim of the study is to evaluate the vulnerability of different water user groups to climate change and define communities' adaptation strategies in the Comoe River Basin. Information was collected on communities' concerns and perception on changes in climate and potential adaptation measures and strategies. Results show that 95 % of the sample in the study communities had heard of it and are aware that climate change is occurring. They have been experiencing changes in economic activity and cropping pattern, reduced water level in rivers, crop failure, delay in cropping season, new pests and diseases, food insecurity, drop in income and decline in crop yield. Results also show that communities employ various adaptation strategies including crops diversification, substitution and calendar redefinition, agroforestry, borrowing from friends and money lenders and increasing fertilizer application.

Integrated hydrologic modeling as a key for sustainable urban water resources planning.

In this study, a coupling of surface water (SWAT), groundwater (MODFLOW) and solute transport (MT3DMS) models was performed to quantify surface-groundwater and quantity-quality interactions under urban area expansion. The responses of groundwater level, nitrate concentrations (related to human activities) and chloride concentrations (related to seawater intrusion) to urban area expansion and corresponding changes in the urban water budget were examined on a macro-scale level. The potentials of non-conventional water resources scenarios, namely desalination, stormwater harvesting and treated wastewater (TWW) reuse were investigated. In a novel analysis, groundwater improvement and deterioration under each scenario were defined in spatial-temporal approach. The quality deterioration cycle index was estimated as the ratio between the amounts of low and high quality recharge components within the Gaza Strip boundary predicted for year 2030. The improvement index for groundwater level (IIL) and the improvement index for groundwater quality (IIQ) were developed for the scenarios as measures of the effectiveness toward sustainable groundwater planning. Even though the desalination and TWW reuse scenarios reflect a noticeable improvement in the groundwater level, the desalination scenario shows a stronger tendency toward sustainable groundwater quality. The stormwater harvesting scenario shows a slight improvement in both groundwater quality and quantity. This study provides a 'corridor of options', which could facilitate future studies focusing on developing a micro-level assessment of the above scenarios.